Self-sealing door assembly for a coke oven

ABSTRACT

A self-sealing door assembly for a coke oven comprises a door frame affixed around the oven opening, the surfaces of the frame facing the oven defining a gap which is filled with heat insulating material, and the outer front surfaces of the frame cooperating with iron sealing strips on the body of the door. The gap filled with insulating material is defined between the vertical and transverse surfaces on the door frame facing the oven and an internal angle-sectioned cover divided around the periphery of the door frame into a plurality of overlapping sections which are supported on distance pieces attached to the surfaces of the door frame.

BACKGROUND OF THE INVENTION

This invention relates to a self-sealing door assembly for a coke oven,comprising a door frame affixed around the oven opening, the surfaces ofthe frame facing the oven defining a gap which is filled with heatinsulating material, and the outer front surface of the framecooperating with sealing strips on the body of the door.

In such types of door assembly for coke ovens, the body of the doorusually has on the oven side iron sealing strips which are mostlyadjustable and are supported on the outer front surface of the doorframe, so as to effect sealing. The sealing is necessary so as toprevent any emissions from within the chamber of the coke oven or tolimit such emissions to a small amount, and to protect the doorcomponents from the thermal stresses associated with these emissions.The door frame is also included in the parts which undergo thermalstress, because it has surfaces on the side facing the oven which liebehind the sealing strips and which are therefore subject to the effectsof heat. To take account of these conditions, a gap is provided betweenthe surfaces of the door frame facing the oven and the brick ovenopening, this gap being filled with heat insulating material.

It is known that the door frames can be produced with various profiles,so as to compensate for thermal stresses. So-called block frame profileswork better than ribbed profiles. It is also known that the effect ofhigh temperatures on cast iron of a certain composition leads to aconversion of the carbide carbon in ferrite and graphite. Thisconversion is associated with a reduction in the strength factors andtherefore leads to damage to the door frame, which can be prematurelydestroyed. In order to meet this problem, the door frame is made in sucha way that it can be replaced.

This invention proceeds from the appreciation that the measures takenhitherto do not take sufficient account of the thermal stresses of thedoor frame. Between the periods in which the oven chamber is loaded, anapproximately constant temperature gradient is formed in the door frameprofile. This means that the temperature difference between the heatradiated from the hot part of the oven chamber and the heat of the doorframe radiated into the atmosphere is approximately constant. The ovenlocks and therefore also the seals can be successfully adjusted to thistemperature gradient, so that during coking time the emissions aregreatly reduced. However, if the charging process is included then thereoccurs a drastic change in the temperature gradient. This is above allto be attributed to the high thermal stress of the surfaces of the doorframe on the oven side during compression of the coke. It leads toone-sided heating of the door frame. This results in lengthwisedistortion which has become known by the phrase "waisting".

Attempts have been made by structural means to secure the door frame tosuch an extent that waisting is at least limited. Shims and clamps,which are used in practice, serve this purpose. However, results by thismeans are comparatively ineffective with regard to distortions caused bytemporary spontaneous heating of the parts facing the oven. Thesedistortions cause the above-mentioned joint of the frame to becomeunsealed, and moreover distort the door frame to such an extent that theoven locks no longer seal. Particularly during the period of the firstcoking phase, increased emissions occur.

The object of this invention is to stabilise the temperature gradient inthe door frame during the charging process, so as to eliminate theabove-mentioned disadvantages.

SUMMARY OF THE INVENTION

According to the invention there is provided a self-sealing doorassembly for a coke oven, comprising a door frame affixed around theoven opening, the surfaces of the frame facing the oven defining a gapwhich is filled with heat insulating material, and the outer frontsurfaces of the frame cooperating with sealing strips on the body of thedoor, said gap being defined between the vertical and transversesurfaces on the door frame facing the oven and an internal cover dividedaround the periphery of the door frame into a plurality of overlappingsections.

During the charging process, the cover, which consists of a materialresistant to high temperatures, prevents a one-sided spontaneous heatingof the door frame by interacting with the insulating material lyingbehind it, whereby the overlapping formation serves as compensation forlinear expansion and at the same time prevents the insulating materialfrom becoming contaminated. Therefore the temperature gradient of thedoor frame during the charging process largely corresponds to thetemperature gradient between the charging processes, during which timethere is a state of thermal stability. The chamber locks which areadjusted to this state can therefore achieve a high degree of sealingdirectly after the charging process so that unnecessary emissions areavoided.

Moreover, the cover has the advantage that it protects the door frameagainst the effects of too high temperatures, so that theabove-mentioned structural transformations in the cast iron material ofthe door frame cannot occur. The working life of the door frame istherefore greatly increased.

Preferably the sections are supported on distance pieces which areattached to the surfaces of the door frame. By this means anapproximately constant cross-section of the gap can be achieved, and thegap can be filled with an insulating material having a low mechanicalstrength, for example, with mineral wool.

The cover is preferably angle-sectioned and has a first flange engagingthe rear of the door frame, a second flange overlapping the surface ofthe door frame facing the opening, and having connected thereto afurther flange which is in alignment with the front surface of the doorframe. The first and further flanges are preferably substantiallyparallel. Such an embodiment assumes that the whole surface of the doorframe on the oven chamber side is available for carrying out theinvention. However, generally this can only be achieved in newinstallations.

If it is desired to use the invention as a modification of existing cokeovens, then generally on the front surface of the door frame there isnot enough room to accommodate both the cover and the gap. It is thenappropriate for the cover to be angle-sectioned and to have a firstflange engaging the rear of the door frame, and a second flangeoverlapping the surface of the door frame facing the opening, whichsecond flange is reduced in thickness at its free end. Then the gap canbe increased at the free end of the flange and more mineral wool can beplaced there so as to increase the insulation accordingly.

In either of the above arrangements the flanges of the cover arepreferably integrally formed as a unit.

Details, further features and other advantages of the invention aregiven in the following description of two embodiments of the invention,which are suitable for carrying out the invention in existinginstallations and in new installations respectively.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a self-sealing chamber door for a coke oven according tothe invention for use in new installations, viewed in partial sectionthrough the closed oven door and the opening of the oven as far as asupporting post,

FIG. 2 is a view corresponding to FIG. 1, showing a self-sealing chamberdoor for a coke oven according to the invention for use in existinginstallations,

FIG. 3 is a diagrammatic perspective view of the door frame,

FIG. 4 shows a cover plate, and

FIG. 5 is a sectional view of an overlap taken along the line V--V inFIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, the brick opening 1 of the oven is provided on itsouter side with a wall protection plate 2, on the outer surface 3 ofwhich is supported the flange 4 on the oven side of an I-sectionedsupporting post 5. The wall protection plate 2 has a peripheral edge 6and between this edge and the oven wall is a gap 7. This gap is filledwith heat insulating material, which is shown at 8. As can be seen fromFIG. 1, the edge 6 is formed from an angled section 9,10 of the wallprotection plate. The free flange of the angled section is given thereference numeral 9, while the other flange 10 leads from the freeflange 9 to the flat section of the wall protection plate 2 and isinclined as it extends outwardly, the parts 2, 9 and 10 being integrallyformed in one piece. The angled section formed by the flanges 9 and 10defines one side of a further gap 11, which is filled with heatinsulating material, as shown at 12. The other side of this gap isdefined by the surface of a vertical post 56 of the door frame 13. Asshown in FIG. 3, the door frame is formed from the post 56, an upperhorizontal cross-piece 59 which extends over the oven opening, aparallel post 57 on the other side of the opening, and a lowercross-piece 58.

The inside of the oven chamber is given the reference numeral 14 and isseparated from the outside by a door 15. The door has a frame 16 made ofcast iron which has flanges 17 directed outwardly. Sealing strips 18made of iron are attached to these flanges, these strips beingadjustable. On the inside 19 of the frame 16 there is a brick support 20which has a covering of insulating material 21.

The door frame posts 56 and 57 are block-shaped, that is, they are eachessentially in the shape of a square or rectangle. As shown in FIG. 1,the shorter side 22 of the rectangle forms, with its outer surface, thefront side of the door frame, whilst the sides 23 and 24 which areapproximately parallel and perpendicular to the side 22 border theabove-mentioned gap 11 with their outer surfaces 25 and 26, and extendtowards the oven chamber. The fourth side of the rectangle is providedwith a re-entrant section 27 and a projecting section 28, correspondingto the angled section 9,10.

As can be seen from FIGS. 1 and 2, the width of the front surface of theframe, which is given by the side 22 of the rectangle, enables a morereliable positioning of the sealing strip 18 on the front side of theframe, taking into account the changes in dimension caused by thermalstresses. In the arrangement of FIG. 1, it has also been taken intoaccount that the width of the side 22 of the door posts, together withthe dimensions of a cover 29 in the same direction, which cover is to bedescribed later, should result in a sufficiently wide door opening.However, this can usually only be achieved in new installations.

A modification of an existing installation is shown in FIG. 2. Here anincrease in the width of the door frame cannot be made without reducingthe width of the door opening to an unsatisfactory degree. Also, thewidth of the side 22 cannot be shortened without too much reduction inthe tolerance for the positioning of the sealing strip 18. A door framein which the width of the side 22 cannot be altered in this way isusually provided in existing installations. The embodiment shown in FIG.2 is for use in such installations.

Referring again to FIG. 1, a cover 29 is arranged on the oven chamberside of the door post 56, and has an angled flange 30 engaging with theprojecting section 28, a flange 31, connected to the flange 30, whichoverlies the surface 26 of the door post, and also a front flange 32,parallel to the flange 30, which is in alignment with the outer surfaceof the side 22. The free edge 33 of the flange 32 has projections 61-63(FIG. 4) each in the shape of a cone or truncated cone, which engage thefront of the surface 26 of the door post, thereby minimising theconduction of heat between the door frame and the cover 29. Severaldistance pieces 34, 35, which are attached on the one side to the flange31 and on the other side to the flange 30, keep the sections of thecover 29 spaced from the corresponding sections of the door frame. Bythis means there is provided a space 36 which is filled with heatinsulating material. According to the embodiment shown in FIG. 1 the gap7 runs around the outer side 37 of the flange 30 and is also filled withinsulating material which is held in a groove 38 in the wall of theoven.

It can be seen from FIG. 3 of the drawings that the cover 29 is composedof individual sections which overlap each other in the manner of scales.Thus, not only are the vertical surfaces 26 of the posts 56, 57 of thedoor frame, on the oven chamber side, provided with sections 50, 51 and52, 53 but also the upper transverse surface of the cross-piece 59 onthe oven chamber side is provided with angle sections 54 and straightsections 55 of the cover 29. The lower cross-piece 58 of the door framehas only the usual wear plate 60. With the exception of the lowercross-piece, a circumferential space 39 is thereby obtained, which isfilled with heat insulating material.

According to the embodiment illustrated, the distance pieces 34, 35which support corresponding flanges 31, 30 of the sections of the cover29, and one door frame itself, are provided with bores 64, 65, 66. Thesebores are in alignment with each other. Usually the bottom of the bore64 is provided with a recess. The head of a bolt is located in thisrecess, the shank of the bolt passing through the registering bores 64,65, 66. A nut is provided on the free threaded end of the bolt withwhich the part concerned is secured. Generally at least three bolts areused along the length of a section. They enable the components to beeasily replaced if necessary, by loosening the nut or bolt.

Adjacent the distance piece 35 there is a blind hole 67 in the door postwhich can be aligned with corresponding bores 68, 69 in the distancepiece 35 and in the flange 30 of the cover 29. As can be seen from FIG.4, all together three bores 68 and 70 and 71 are provided. Together withthe above-mentioned bores 64 they lie in common transverse planes,whereby the middle projection 62 of the top of each section is arrangedin a common transverse plane with the bore 70. The purpose of the bores68, 70, 71 is to receive tightening bolts which are not shown, which fixthe sections at these points. The tightening bolts enable the sectionsto be easily replaced if they become worn.

The sections of the cover are mounted in such a way that they overlap inthe manner of scales, as can be seen in FIGS. 3 and 5 where sections 52,53 are shown by way of example. Cooperating tongues 76, 77 are definedby rebates in the adjacent edges 74, 75 of consecutive sections 52, 53.These tongues run along the whole length of the actual edge and are sodimensioned that together they form the thickness of the sections. Onthe other hand their length is adjusted so that the thermal variationsin length of the sections can be taken into account.

According to the embodiment shown in FIG. 2, the profile of the doorframe differs from the profile of the embodiment in FIG. 1 insofar asthe longer side 24 of the rectangle is not continuously straight. On thecontrary it ends in a projection 40 which is square in cross-section andwhich projects from the surface 26. It is therefore not possible to usethe outer surface 41 of this projection 40 for bordering the space 36.According to this embodiment, therefore, the space 36 ends at the innershoulder 42 of the projection 40. Moreover, the flange 31 of the cover29 has a rebate 44 at its free end, that is, an undercut, whereby theend portion 45 of the flange 31 is in the form of a tongue, that is, thestrength of its wall is reduced in comparison with the other areas ofthe flange 31. There is thereby produced an angular extension 46 of thespace 36, which is filled with insulating material.

The cover 29 and door post are thus formed in such a way that they canbe used in already existing coke ovens.

The cover 29 consists of heat-resistant material, whilst the filling ofthe space 36 can be effected with mineral wool as the insulatingmaterial.

We claim:
 1. A self-sealing door assembly for a coke oven comprising adoor frame and a door having a body, said door frame being affixedaround the oven opening, the surfaces of the frame facing the ovendefining a gap that is filled with heat insulating material and theouter front surfaces of the frame cooperating with sealing strips on thebody of the door, said gap being defined between the vertical andtransverse surfaces on the door frame facing the oven and an internalcover divided around the periphery of the door frame into a plurality ofoverlapping sections, said cover being angle-sectioned and having afirst flange engaging the rear of the door frame, a second flangeoverlapping the surface of the door frame facing the opening, and havingconnected thereto a further flange that is in alignment with the frontsurface of the door frame, said first flange being provided with boresfor receiving clamping bolts, and said second flange being provided withbores for receiving clamping bolts and with projections, each in theshape of a cone, for engagement with the door frame.
 2. A self-sealingdoor assembly according to claim 1, wherein the sections are supportedon distance pieces which are attached to the surfaces of the door frame.3. A self-sealing door assembly according to claim 1 wherein the firstand further flanges are substantially parallel.
 4. A self-sealing doorassembly according to claim 1, wherein the flanges of the cover areintegrally formed as a unit.
 5. A self-sealing door assembly accordingto claim 1, wherein the second flange is reduced in thickness at itsfree end.
 6. A self-sealing door assembly according to claim 5, whereinthe flanges of the cover are integrally formed as a unit.